The magnetic sensor is a device for converting changes in the magnetic characteristics of the sensing elements caused by magnetic field, current, stress strain, temperature or light into electric signal, so as to measure related physical quantities, particularly minute physical quantity. Compared to conventional sensors, the magnetic sensor has the advantages such as high sensitivity, and is therefore widely used in navigation, spaceflight, geological prospecting, medical imaging, information collection and military applications.
With the development of technology, the magnetic sensor chip becomes the core component of the magnetic sensor for the advantages such as low power consumption, small size, high sensitivity, integratable attribution, low costs, fast response, high resolution, good stability and high reliability. The utilization of the magnetic sensor chip spreads the applications of the magnetic sensor in magnetic information storage, automation and the Internet of Things.
FIG. 1 depicts the structure of a conventional magnetic sensor chip. As shown in FIG. 1, the magnetic sensor chip comprises a magnetic sensitive film 2 and a conductor 3, the conductor 3 is provided at two ends of the magnetic sensitive film 2 for connecting to other components. During the operation of such magnetic sensor chip, the demagnetizing field of the magnetic sensitive film 2 may be large because of the large ratio between the length and width thereof. Therefore, the magnetic sensor chip suffers severe hysteresis. FIG. 2 shows a curve of the hysteresis loop of the conventional magnetic sensor chip, wherein the lateral axis represents the intensity (H) of the applied magnetic field, and the vertical axis represents the resistance (R) of the magnetic sensor chip. As shown in FIG. 2, the hysteresis loop of the magnetic sensor chip has a large width, i.e. the magnetic sensor chip has large hysteresis, which reduced the sensitivity of the magnetic sensor chip.